The present embodiments relate to a standing wave trap for a magnetic resonance tomography (MRT) system.
Magnetic resonance tomography devices for examining objects or patients using magnetic resonance tomography (MRT, MRI) are known, for example, from DE 10314215B4.
In magnetic resonance tomography, RF coils (local coils) are used to receive alternating magnetic fields. In order to obtain a good signal-to-noise ratio at all times, the geometry and reception profile, for example, of the RF coil are adjusted to optimize the RF coils for different regions of a patient's body. To achieve the highest possible signal-to-noise ratio, local coils are generally positioned as close as possible to a patient's body.
Local coils are implemented, for example, as receive-only coils, and the spins are excited using a body coil (whole-body resonator) of an MRT system. Signals are transmitted from the local coils to the receiving system of an MRT facility via a local coil feeder cable, such as an RF cable. In the transmit phase, RF currents are induced on the cable shield of the local coil feeder cable by the E and B fields in an MRT system. Induced RF currents on, for example, local coil feeder cables are referred to as standing waves. Standing waves are undesirable and may lead to image interference. Worse yet, standing waves may even present a hazard to the patient.
Standing wave traps (SWTs) are inserted into the local coil feeder cable of the local coils in order to suppress radio-frequency currents (standing waves) on the outer conductor of local coil feeder cables. A standing wave trap is a highly resistive impedance for the RF wave and, consequently, suppresses the RF current on the local coil feeder cable.